The present invention relates to a tape cartridge for recording computer data and the like, and more particularly relates to a tape cartridge in which a magnetic tape is wound onto a hub.
The basic structure of the tape cartridge in which the magnetic tape is wound onto the hub is publicly known, for example, in JP 6-97549 B (see 20th line in left column on third page, FIG. 3). Therein, the tape feed structure is disclosed in which hubs are placed on the right and left sides in a main casing, and a magnetic tape unreeled from one hub is reeled onto the other hub. A hub locking structure is provided inside the main casing for regulating rotation of the hub during unused time to prevent tape slacks.
The hub locking structure is composed of a lock gear having lock teeth in a gear teeth shape formed on the peripheral surface, a lock frame sliding and shifting back and forth, a lock claw integrally formed with the lock frame for engaging with and disengaging from the lock gear, and a spring for biasing and moving the hook frame toward the lock gear. Component parts except the lock gear are built into the inner surface of the upper case. It is to be noted that the lock gear is molded integrally with the hub.
In the tape cartridge structured to have the magnetic tape wound onto the hub, the upper surface and the undersurface of a tape winding layer wound onto the hub are exposed to the inside of the main casing unlike the tape reel having upper and lower flanges. Therefore, when the tape cartridge receives dropping impact, there is a possibility that the tape winding layer may collide with the inside wail of the main casing and the tape edge may be damaged. In order to reduce contact friction of the tape winding layer at the time of rotational driving, slippery sheets are placed on the upper and lower walls inside the main casing, so that the damage of the tape edge can be prevented by the slippery sheets to some degree.
However, if a hub locking structure is placed at the anterior portion of the inner surface of the upper case, the anterior side of the tape winding layer is supported by the lock frame through the slippery sheet, in the state where the upper and lower sides of the tape cartridge are reversed, and therefore the hub and the tape winding layer are supported in an inclined state. Consequently, in the case where the tape cartridge receives dropping impact in the state of its upper and lower sides being reversed, the area near the rim of the posterior portion of the tape winding layer may collide with the case wall, which may cause the tape edge to be damaged or cause a part of the outside of the tape winding layer to shift toward the shaft center of the hub.